Abstract : The distortions of speech in a helium-breathing mixture are analyzed with the aid of an analog ear having time resolution sufficient to reveal temporal details of neural volleys as are produced by individual glottal pulses. The several existing techniques for helium speech correction are reviewed. Due to excessive weakening of second formants in helium concentrations greater than 80%, and certain other factors, it is concluded that no scheme yet proposed is likely to be satisfactory in a practical noisy environment. (Author)